First-principles study of oxygen vacancies in Lu2SiO5

We investigated the oxygen vacancies in Lu2SiO5 (LSO:Ce) by using first-principles pseudopotential calculations based on density functional theory. The results indicate that VO5 has the lowest formation energies compared with the other four oxygen vacancies belonging to the SiO4 tetrahedron. The oxygen vacancy can induce extra states in the band gap. The 2+ charge state vacancies are energetically favorable and show lower formation energies with respect to the neutral vacancies. VO5 could act as electron trap which could be responsible for the afterglow emission for LSO:Ce.